Embodiments of the invention generally relate to a wind power generation system and, more particularly, to a system and method for controlling a wind power generation system.
Wind turbines are used to generate power by harnessing wind energy present in the environment. During operation, the wind turbines experience various undesirable loads which are mitigated using different approaches. Loads experienced by the wind turbines may include loads induced by the wind and loads induced by a fault condition on a grid connected to the wind turbines. The loads induced by the wind may be minimized by adjusting wind turbine components such as blade pitch control units and yaw motors. The loads induced by the fault condition on the grid may be mitigated by design parameters such as size and fabrication material as well as operating parameters such as pitch angles of wind turbine blades.
During a fault condition on the grid, an electromagnetic torque in the wind turbine may increase suddenly and may be followed by an over speeding event of a rotor of the wind turbine due to loss of power at an output. In such circumstances, the over speeding event and the sudden increase in the electromagnetic torque induce mechanical loads in the wind turbine. The wind turbine includes a pitch control unit that is configured to control a pitch angle of the wind turbine blades. The pitch control unit changes the pitch angle of the wind turbine blades to reduce the mechanical loads. However, if a rate of change of pitch angle is greater than a predefined rate of change of pitch angle, the wind turbine components may experience severe oscillations. The tower of a wind turbine is particularly susceptible to oscillations, and tower oscillations reduce life of the wind turbine and increase maintenance costs.
Wind turbine components such as towers, drivetrains, and gearboxes are typically designed to withstand aforementioned mechanical loads that are induced due to potential fault conditions on the grid. For example, gearboxes are designed to withstand a peak electromagnetic torque up to three times of a nominal operating torque. Such designs lead to larger gearboxes and increased costs.
Hence, there is a need for an improved system to address the aforementioned issues.